Intracranial hypertension is a primary cause of secondary injury in head injured patients and a major prognostic indicator targeting patients at risk for mortality and poor functional outcomes. Cerebrospinal fluid (CSF) drainage is a medical intervention for elevated intracranial pressure (ICP) in patients with head trauma that nurses initiate and make independent decisions including the timing, frequency, and amount of CSF drainage. With the lack of empirical data, standards for CSF drainage are inconsistent thus leaving nurses with no scientific rationale for this practice. The purpose of this study is to determine if CSF drainage decreases ICP and improves cerebral perfusion in head injured patients. This study is the investigator's second study within a broad plan to ascertain the effects of nursing interventions in head injured patients on cerebral function. This study will compare the cerebrovascular responses of head injured patients to three CSF drainage protocols using both traditional and advanced neurophysiologic methods available to nurse clinicians to evaluate the response. The research questions are: 1) Does CSF drainage improve ICP and cerebral perfusion [as measured by cerebral perfusion pressure (CPP), cerebral blood flow velocity (Vmac) and oxygen tension in the jugular bulb (PjO2]? 2)Is there a difference in the change in ICP and cerebral perfusion by the amount of CSF drainage (1,2 and 3 mL)? and 3) Is there a difference in the hemodynamic responses [system arterial pressure (SAP) and heart rate (HR)] before and after CSF drainage? Secondary aims of this study are to compare in post hoc analysis the traditional methods monitored continuously in the clinical area for assessment of cerebrovascular responses (ICP and CPP) with advanced neurophysiologic methods (Vmac and PjO2) and to identify any moderating effects from age, total volume and frequency of CSF drainage prior to initiation of CSF drainage protocol, baseline arterial carbon dioxide levels, medications, temperature and type of head injury on the efficacy of CSF drainage. This within-subject, repeated measures design will randomize 3 protocols of CSF drainage in 60 head injured patients. The independent variable is the CSF drainage (1 mL, 2 mL, 3 mL). Simultaneous real time data on physiologic parameters (SAP, ICP, HR, SpO2, Vmac, P/ET CO2) are continuously acquired and recorded before, during and following the CSF drainage protocols. SAP and ICP are measured using pressure transducers connected to Gould amplifiers and calibrated against a column of mercury. HR is collected by connecting EKG limb leads to a Gould amplifier. Vmac is measured using a transcranial doppler attached to a Gould amplifier. PjO2 and SpO2 are validated by blood gases. Amplifiers transmit analogue data to a computerized Gould Data Acquisition and System Analysis program for analogue to digital transformation and analysis. Multivariate and repeated measure analysis of variance will determine the most effective CSF drainage method for decreasing ICP and preserving cerebral perfusion.